I would love to see this evidence.From recovery Plan page 2:
Compelling evidence of the species’ existence was obtained when the Ivory-billed Woodpecker was reported in Arkansas and presented by Fitzpatrick et al. (2005). On February 11, 2004, kayaker Gene Sparling observed a large woodpecker with characteristics of an Ivory-billed Woodpecker in Arkansas. The encounter spurred an extensive search led by the Cornell Laboratory of Ornithology and the Arkansas Nature Conservancy. In 2004 and 2005 observers reported multiple sightings and recorded audio and video interpreted to be an Ivory-billed Woodpecker within the same area as Sparling along Bayou DeView, located in the Cache River National Wildlife Refuge (NWR) in east-central Arkansas. Interpretation of the video has been challenged by others (Jackson 2006, Sibley et al. 2006).
USFWS ES Recovery Plans do NOT present evidence although some might be in there. For example you will not see much or anything about the book-like stack of evidence of Ivory-bills existence recently from Florida of ~ 4 birds by Auburn and Windsor University (many sets of field notes, hundred of knocks and kents by ARUs and people, videos, roost measurements) . You will not see much or any of the evidence from LA, Louisiana, by multiple researchers (Videos independently confirmed by peers as IBWO, several papers, audio, stills, field notes, field logs etc).
I assure you IBs existed after the Recovery Plan was out ten years ago. See upthread in last 2 threads by the way for comments on how skeptics watered down the effectiveness of the paid for surveys. The surveys used erroneous methods and relatively inexperienced surveyors. The whole thing was a typical government fiasco.